A consortium of scientists reported on Wednesday that they had identified new potential treatments to combat a form of sleeping sickness that kills around 30,000 Africans a year.

The breakthrough entails disabling an enzyme essential for the parasite causing human African trypanosomiasis (HAT), as the disease is called.

Further work is needed to narrow down the shortlist of candidates for the orally-taken drug, and the most promising one could be available for human trials "in around 18 months," the team said in a press release.

Between 50,000 and 70,000 people in sub-Saharan Africa are infected with HAT, which is transmitted in the bite of the tsetse fly, according to World Health Organisation (WHO) estimates.

It is sometimes called sleeping sickness because the parasites infect the brain and disrupt the sleep cycle.

Two drug types already exist for tackling HAT, but are laden with problems.

One, melarsoprol, is an arsenic-based treatment that kills around five percent of patients.

The other, eflornithine, is costly, requires long hospital treatment, is not effective against all forms of the disease and appears to be encountering parasite resistance.

Because people infected with HAT are generally the rural poor, there is little motivation for pharmaceutical companies to search for new drugs, which makes the disease high on the WHO's list of so-called neglected sicknesses.

The paper, published in the British journal Nature, was led by the Drug Discovery Unit for Tropical Diseases at the University of Dundee, Scotland. Researchers from the University of York and the Structural Genomics Consortium in Toronto also took part.

Another form of trypanosomiasis, called Chagas disease, is prevalent in 15 Central and South American countries. It is spread by blood-sucking triatomine bugs that hole up in walls and roofs and feed on the victim's face at night.